1. Field of the Invention
The present invention is concerned to a bone resorption inhibitor consisted of a leukocyte activating protein factor or a substance originating therein. A screening method against therapeutic for hypercalcemia, osteoporosis.
2. Description of the Prior Art
A leukocyte activating protein factor (hereinafter referred to LECT2 [Leukocyte-derived chemotaxinm 2]) has been found as a neutrophil chemotactic factor (Laid-open Patent publication No. Hei8-140683). Gene of human and bovine LECT2s have been cloned and their sequences have also been determined (S. Yamagoe et al., Immunol. Lett. 52, 9-13, 1996 S. Yamagoe et al., Biochem. Biophys. Acta, 1396, 105-113, 1998). mRNA of human LECT2 codes 151 amino acids containing 18 amino acids sequence for its signal peptide. Amino acid sequences of ovine and human LECT2s show the higher homology to min-1 gene product derived from chicken. The min-1 product is contained in promyelocytes in the bone marrow and relates to generating control of oncogne myb, although its biological function has not been determined.
Action of LECT2, which was found as a chemotactic factor, is thought to use for diagnosis, therapy and follow up the diseases such as cancer, because increase of tumoricidal activity and production of interleukins from leukocytes due to activation of neutrophils with LECT2. Now, it is known that LECT2 only acts on neutrophils, action on bone metabolism has not, been reported (Protein, Nucleic Acid and Enzyme-Tanpakushitu-Kakusan-Koso 42, 1086, 1997).
On the other hand, Fujio Suzuki et al. (Y. Hiraki et al., J. biol. Chem. 271, 22657-22662, 1996) isolated Chondromodulin-II, which is approximately 16 kDa protein from chondrocytes of fetal bovine. It is disclosed that Chondromodulin-II shows a promotion for proliferating chondorocytges and its differentiation (Laid open Patent publication No. H5-255398) and that chondromodulin has a promotion for proliferating osteoclast and has an act for activating osteoclast (Laid-open Patent Publication No. H8-27020). Recently, according to study on homology, it was found that Chondromodulin-II is the same as that of LECT2.
Osteoclasts, which are polynuclear large cells, act an adsorpting bone in bone tissues, thereby taking important part in re-modeling bone. Precursor cells will be derived from stem cells, and translocated on bone surface through circulated blood thereby being differentiated to osteoclast. On the other hand, osteoblast are differentiated from precursor cell, which belongs to stroma forming cells such as immature mesenchymal cells, fibroblasts and interstitial cell, and are derived from precursor of different cell line from those of osteoclasts. Bone forms by remodeling according to formation and resorption of bone repeatedly. Organizationally, remodeling of bone is carried out by resorpting, and, then, re-synthesizing bone from osteoblast, under reasonable balance. With aging, the balance change is occurred due to imbalance conditions of the metabolism, the weight of bone is decreased. With the continuation of this condition for long time, bone tissues get weak and cause osteoporosis, destruction of bone or pain in lumbars.
As agents against resorption of bone estrogen, calcitonin, bisphosphate and the like have been used, however side effects are also reported.
Accordingly, highly effective for inhibiting resorption of bone due to osteoclast and highly salty agents have been desired.
According to hard study, the inventors found the bone resorption inhibitor on osteoclasts, and eminently succeeded the invention.
An object of the present invention is to provide a novel bone resorption inhibitor.
Another object of the present invention is to provide the bone resorption inhibitor containing effective amount of substance derived from LECT2 or LECT2 derived substances.
Further object of the present invention is to provide the bone resorption inhibitor containing LECT2 or LECT2-derived substances involving sequences of amino acid number 1 to 151 or 19 to 151.
Still another object of the present invention is to provide the bone resorption inhibitor containing leukocyte activating protein factor or leukocyte activating protein factor-derived substances.
Still further object of the present invention is to provide screening methods for bone resorption inhibitors derived substances containing leukocyte activating protein factor or leukocyte activating protein factor-derived substances.
Still further object of the present invention is to provide the bone resorption inhibitors showing the inhibitory activity by more than 80% at a concentration of 10 xcexcg/ml in the screening methods pit formation mentioned above for bone resorption inhibitors in the candidate substances.
Still further object of the present invention is also concerned use of leukocyte activating protein factor or leukocyte activating protein factor-derived substances in the production of bone resorption inhibitors.
Still further object of the present invention is also concerned methods for treatment in animals with bone resorption inhibitors derived substances containing leukocyte activating protein factor or leukocyte activating protein factor-derived substances.
A main feature of the present invention is to find that LECT2 or LECT2-derived substances posses bone resorption inhibiting activity.